In a wireless local area network (Wireless Local Area Network, WLAN for short) system, a station (Station, STA for short) with a high energy saving requirement, for example, a sensor station, may exist. In a standard, a power saving (Power Saving, PS for short) mode of an STA is defined. An STA selecting the PS mode may sleep for one or more beacon (beacon) intervals. When an access point (Access Point, AP for short) caches data of the STA, the access point notifies the STA by using a beacon. The STA may request to obtain the cached data from the AP by using a power saving polling (Power Saving Polling, PS-POLL for short) frame. A level of the PS-POLL frame is Access Category-Best Effort (Access Category-Best Effort, AC-BE for short), and a corresponding transmission opportunity (Transmission Opportunity, TXOP for short) is zero, that is, only one data frame is allowed to be transmitted. If the STA intends to send uplink data to the AP after receiving downlink data sent by the AP, channel contention needs to be performed again to establish a new TXOP, thereby causing resource waste for the STA with a high energy saving requirement.